A restraint system for a head-on collision of a vehicle is known from DE 198 60 827 A1, having an airbag that is mounted at the vehicle roof and which unfolds in the manner of a curtain when corresponding sensor data are present. To ensure the positional stability of the unfolded airbag, a partial region of the front fabric section of the airbag is supported on the vehicle bodywork. For this purpose the configuration is chosen so that the airbag unfolds forward and downward along the upper region of the windshield, and then in the direction of the vehicle occupant. In one variant, a fillable curtain is provided on which a chest section and a head section are situated, each of which is separately connected to the curtain and separately fillable.
In a forward motion of the vehicle occupant as the result of a head-on collision, the airbag, which extends to the abdominal region of the vehicle occupant, is wedged between the thigh and the upper body and remains in a fixed position relative to the head. In addition, the airbag is fixed in place in the roof region of the vehicle, so that very high tensile stresses occur in the airbag fabric when the vehicle occupant penetrates the airbag. This results in a relatively hard impact and high strain on the head and neck, possibly even snapping the head backwards.